Special relativity was unified with quantum mechanics in the 40s. The result is called quantum field theory; it's the most successful physical theory we have.

Special relativity was unified with quantum mechanics in the 40s. The result is called quantum field theory; it's the most successful physical theory we have. Attempts to quantize general relativity abound. A handful which anyone interested will mention off the top of their head: http://www.forbes.com/sites/startswithabang/2015/12/17/what-are-quantum-gravitys-alternatives-to-string-theory/#4f343e313f75 http://www.forbes.com/sites/startswithabang/2015/12/17/what-... The problem is not just conceptual or mathematical, it's a total lack of experimental data. Even if you write down the correct theory of quantum gravity, you have no realistic way to test it - but you can rest assured that everybody pursuing a different approach will be right there telling you that you are an idiot.